The eight people were sailing a vessel on Nam Thach Han irrigation dam on the Thach Han River in the central province at around 9 a.m. when it broke down, stranded on a large weir.
To avoid being swept away by the raging torrents of water, resulted from heavy downpours in the central region on recent days, they jumped over a concrete divider in the middle of the dam.
But Hoang Duc Viet, 47, director of a local excavation firm, missed it and was swept away. He remains missing.
Seven others including Tran Ngoc Son, deputy director of Quang Tri's Transport Department, were rescued brought ashore at 2:30 p.m. Rescuers used small boats to approach them.
Authorities are still looking for the missing person.